Cristiano Ronaldo's move to Juventus was due to his "obsession" with Barcelona's Lionel Messi, according to ex-Manchester United winger Ryan Giggs.

Ronaldo made the switch to Turin on Tuesday for a transfer fee of €100 million as Bianconeri manager Massimiliano Allegri looks to launch a challenge on the Champions League next season, a trophy they have not won in 22 years.

"I'm surprised, surprised that he would leave Real Madrid and go to Italy," Giggs told ITV.

"I think it's a big challenge for him but he's going to a huge club. Having that on your CV... Real Madrid, Man United and Juventus. It's some CV. It will be a challenge for him at 33.

"He's obsessed at being better than Messi. I did it in England, I did it in Spain, I'm going to do it in Italy. I did it with Portugal. So maybe that will be his argument when [he thinks about] 'Am I better than Messi'?"

Ronaldo's move raises questions over Gareth Bale's future after he helped Real Madrid to the Champions League last May. But Giggs can't imagine the Spanish giants allowing two superstars leave this summer.

"No, you wouldn't [want to lose Bale as well]," Giggs added. "Gareth, obviously the impact he had at the end of last season but I am sure Real Madrid will be looking at the likes of Neymar and [Kylian] Mbappe because obviously they have €100 million burning a hole in their pocket."